Sensor systems, such as nuclear magnetic resonance (NMR) gyroscopes and magnetometers and/or electron paramagnetic resonance (EPR) magnetometers, can include a cell that contains one or more alkali metal vapors, such as rubidium or cesium, together with one or more nuclear spin isotopes that are caused to precess in response to a magnetic field. The alkali metal vapor(s) can be stimulated to an excited state in response to optical pumping in a given frequency band. Thus, the alkali metal vapor can be subject to AC Stark shift, in which the atoms of the alkali metal vapor are optically pumped with light that is off resonance with respect to an atomic transition wavelength, causing a virtual magnetic field to be experienced by the alkali metal vapor but not by the nuclear spin isotopes. The resultant effect of the AC Stark shift is an added bias in the detected magnetic field of the associated magnetometer or an added bias in the rotation angle and/or rate of the associated gyroscope, and thus errors in their respective measurable parameters. Because alkali metals have two independent ground states, and thus two separate atomic transition frequencies, AC Stark shift is unavoidable in the optical pumping of the alkali metals.